package com.util;

import java.security.MessageDigest;  
import java.security.NoSuchAlgorithmException;  
import java.util.Arrays;  

/** 
* 请求校验工具类 
*  
* @author liufeng 
* @date 2013-05-18 
*/  
public class SignUtil {  
  // 与接口配置信息中的Token要一致  
  private static String token = "weixinwwl";  

  /** 
   * 验证签名 
   *  
   * @param signature 
   * @param timestamp 
   * @param nonce 
   * @return 
   */  
  public static boolean checkSignature(String signature, String timestamp, String nonce) {  
      String[] arr = new String[] { token, timestamp, nonce };  
      // 将token、timestamp、nonce三个参数进行字典序排序  
      Arrays.sort(arr);  
      StringBuilder content = new StringBuilder();  
      for (int i = 0; i < arr.length; i++) {  
          content.append(arr[i]);  
      }  
      MessageDigest md = null;  
      String tmpStr = null;  

      try {  
          md = MessageDigest.getInstance("SHA-1");  
          // 将三个参数字符串拼接成一个字符串进行sha1加密  
          byte[] digest = md.digest(content.toString().getBytes());  
          tmpStr = byteToStr(digest);  
      } catch (NoSuchAlgorithmException e) {  
          e.printStackTrace();  
      }  

      content = null;  
      // 将sha1加密后的字符串可与signature对比，标识该请求来源于微信  
      return tmpStr != null ? tmpStr.equals(signature.toUpperCase()) : false;  
  }  

  /** 
   * 将字节数组转换为十六进制字符串 
   *  
   * @param byteArray 
   * @return 
   */  
  private static String byteToStr(byte[] byteArray) {  
      String strDigest = "";  
      for (int i = 0; i < byteArray.length; i++) {  
          strDigest += byteToHexStr(byteArray[i]);  
      }  
      return strDigest;  
  }  

  /** 
   * 将字节转换为十六进制字符串 
   *  
   * @param mByte 
   * @return 
   */  
  private static String byteToHexStr(byte mByte) {  
      char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };  
      char[] tempArr = new char[2];  
      tempArr[0] = Digit[(mByte >>> 4) & 0X0F];  
      tempArr[1] = Digit[mByte & 0X0F];  

      String s = new String(tempArr);  
      return s;  
  }  
}
